Field of Search: 351/200,211-221,206,245,246
The slit lamp biomicroscope is widely considered an essential diagnostic instrument in the field of opthalmology and consists of two principal components: a bright focal source of light projecting an illuminating beam whose cross section forms a slit of variable width or height; and a microscope, usually binocular to view the area of interest illuminated directly or indirectly by the slit beam.
The corneal binocular microscope component was the first to be developed and has been attributed to Aubert in 1891 who enhanced Louis de Wecker's monocular microscope invention. Siegfried Czapski's refined this instrument into a corneal surface microscope with stand, developed by Zeiss in 1899. The first instrument to feature slit illumination appears to have been that developed by Allvar Gullstrand (1862-1930) and demonstrated at Heidelberg in 1911.
Henker and Vogt improved upon Gullstrand's device in the 1910s by creating an adjustable slit lamp and combining Czapski's microscope with Gullstrand's slit lamp illumination to develop the Zeiss Slit lamp in 1916. This resulted in a binocular microscope coupled, around the same axis, with a bright light source allowing different illuminations and magnified views of the eye.
In 1933, Hans Goldmann (1899-1991) working under Professor Siegrist of Bern, devised a joystick controlled mechanism to focus the illumination system and the corneal microscope components together in a coordinated manner.
The slit lamp biomicroscope was thus established as an essential diagnostic tool by the Opthalmology community and subsequently enhanced and adapted to allow additional diagnostic and therapeutic functions including digital imaging and laser delivery.
Varieties of tables for supporting a slit lamp microscope and associated ophthalmic instruments have been developed over the years and are known in the art. In the prior art, a slit lamp assembly generally included a base set upon a table with means to adjust the table height and position to accommodate the particular individual whose eyes were being examined.
Ophthalmic examination takes place by use of the slit lamp biomicroscope which normally sits upon the top side of the table. When being examined, the patient must place his or her chin on a chin rest and must rest his or her forehead on a forehead support both supporting structures being attached to the slit lamp table. The proper placement of a patient's chin and forehead is essential to ensure the patient's head and eyes remain in a steady position in relation to the slit lamp biomicroscope. In addition a movable slit illumination system is necessary whose vertical axis of rotation is fixed in relation to the focal point of the binocular lens eyepiece system of the slit lamp biomicroscope so that the details of the eye can be both properly illuminated and viewed.
The prior art slit lamp biomicroscope assembly includes a table, generally rectangular in shape, located underneath the slit lamp biomicroscope. The table requires certain minimum dimensions to allow translation (controlled movement), support, placement and fixation of the slit lamp biomicroscope in order to perform examination and treatment of the eyes being studied. The table base beneath the slit lamp biomicroscope is integral to the prior art slit lamp assembly as no known method has been proposed to allow proper placement and translation of the slit lamp biomicroscope and its integral variable slit illumination system in the absence of a table beneath the slit lamp biomicroscope.
In the prior art, the table also supports chin rests and forehead supports to allow proper and steady positioning of the patient in relation to the slit lamp biomicroscope Although gross adjustments in the positioning of the table, height of the chin rest and height of the patient's chair and doctor's stool are necessary to accommodate individual patients, there remains the necessity of fine adjustments to the position of the slit lamp biomicroscope even after the patient has been properly positioned so that the field of view under high magnification can be focused on details on and within the eye and so that both the left and right eyes can be properly viewed without obstruction or shadows cast by the patient's nose.
The need for adjustments in the position of the slit lamp biomicroscope after the patient's head has been properly positioned has been satisfied in the prior art by allowing limited movement of the slit lamp biomicroscope in relation to the table by base by means of rolling or sliding mechanisms, using gears or cogs, and manually controlled by a joystick to move the slit lamp biomicroscope in relation to the table base.
Although the prior art is satisfactory for examining the majority of patients, a considerable and growing number cannot be satisfactorily positioned and examined due to anatomical obstructions caused by the integral table base. The table base poses a hindrance and impairs proper positioning in the case of “Restricted Individuals” such as:                i. a disabled person confined to a wheel chair or stretcher,        ii. a person with limited neck mobility or spine disorder such as kyphosis or scoliosis,        iii. an ample bosomed individual,        iv. a pregnant woman,        v. an overweight or obese person,        vi. a person of short stature or a child who has to bend forwards in an elevated examining chair and adopt a hunched posture to reach the chin rest and forehead support,        vii. a person with a stoma or wound dressing on their abdomen or chest or requiring medical devices attached to their neck or torso.        
Even though the prior art slit lamp biomicroscope assemblies can be positioned close to a patient in a wheel chair rather than one seated in an exam chair, the sides of the wheelchair as well as the wheelchair's limited vertical mobility continue to present obstructions to examination.
Various attempts have been made in the prior art to overcome the difficulties of examining patients listed in the above categories with a slit lamp biomicroscope. These include modifications of the table base dimensions to reduce the space that the table occupies between the slit lamp biomicroscope and the patient. Such modifications have limited utility as they only moderately reduce the ergonomic obstacle at best, and concurrently reduce the desired mobility and stability of the supported slit lamp biomicroscope.
The only known prior art slit lamps not dependent on the previously described conventional table base assembly consist of hand held slit lamps which are small instruments supported and positioned by hand in front of the patient. The movement and positioning of such hand held slit lamps in all three spatial axes is dependent entirely on the hand and arm muscle movements of the observer holding the miniature slit lamp. Therefore, such devices cannot be accurately positioned or fixed due to normal physiological limitations Furthermore, since only one of the examiner's hands is left free proper bimanual (two handed) manipulation of the slit lamp and illumination controls is not possible.
It is important to note that examples exist in the prior art of binocular microscopes that do not require a table base and can be controllably positioned. However the present invention is to be distinguished from such prior art since it relates to a slit lamp biomicroscope, which by virtue of its variable slit illumination system serves a different function and has distinctly different components. Furthermore such prior art microscopes are not associated with chin rests or forehead supports since their utilization in opthalmology and other specialties is generally restricted to use in surgery when the patient is recumbent and immobilized.
Accordingly, it is the primary object of the present invention to provide a table-free assembly for a slit lamp biomicroscope, laser or similar ophthalmic instrument consisting of an overhead mount or canopy above the slit lamp biomicroscope which eliminates ergonomic impediment and significantly reduces anatomical barriers whilst retaining precise control of focusing, illumination and positioning, thereby allowing examination of categories of patients who cannot be properly examined using traditional prior art.
It is the further object of the present invention to provide a slit lamp biomicroscope assembly with a translation, fixation and support system located above the slit lamp biomicroscope and its integral variable slit illumination system, thereby allowing accurate and safe positioning and placement of the slit lamp (or other similar instrument) while leaving both hands of the observer free to manipulate lighting and other controls necessary to examine and treat the eyes being observed.
It is the further object of the present invention to provide a table-free slit lamp assembly located above the slit lamp biomicroscope or other similar instrument which is relatively inexpensive and easy to manufacture and more patient friendly as compared with the prior art.
Other objects and advantages of the present invention will become obvious to the reader and it is intended that these objects and advantages are within the scope of the present invention.
To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims.